1. Field of Invention
The present invention relates to an intelligent cable system with a built-in sensor, applicable to a cable bearing structure such as a cable-stayed bridge, a suspension bridge, and an arch bridge.
2. Related Art
A cable system of a modern long span bridge is a core component of a cable-stayed bridge and a suspension bridge, and self weight of the long span bridge and a dynamic load on the bridge are mostly delivered to a pylon column through the cable system, and therefore, an operation state of the cable is one of important signs directly reflecting whether the bridge is in a safe state. However, due to construction design, environmental corrosion, or fatigue accumulation, damage and deterioration of different degrees unavoidably occur to the cable in service. If a sensor is organically integrated into the cable, so that the cable can measure parameters such as an internal stress and temperature, and the cable is upgraded from a cable with pure bearing to an intelligent cable having an automatic sensing capability, and meanwhile, the possibility of monitoring the overall stress and partial wire stress of the cable is realized, it further facilitates people to master the structural safety and operation state of the cable and the whole bridge, and find an accident omen in time, thus preventing a sudden accident from happening. A fiber grating is a sensitive element with excellent performance, and senses external slight strain change through movement of Bragg reflection wavelength, so as to realize on-line monitoring of the parameters such as the structural stress and the temperature. The fiber grating has the characteristics of harsh environment endurance, immunity to interference of environmental noise, anti-electromagnetic interference, integration of sensing and transmission, simple structure, convenient use, and high measurement precision. However, the fiber grating without special treatment is very frail, and is easily broken if it is directly laid in the cable. The combination of the fiber grating and the cable involves the problems such as how and in which form the fiber grating is packaged, so as to improve survival rates of the fiber grating sensor and the fibers in cable manufacturing and application processes; how to build the packaged fiber grating sensor in the cable, so as to ensure reliability of the embedding technology of the fiber grating sensor; and how to effectively lead a fiber grating signal out of a cable body without distortion.